Accelerating of hardening of plastic protein articles



Patented July 27, 1943 ACCELERATING F HARDENING 0F rmsrrc rno'mm narrows Silvio Pellerano, Brooklyn, N. Y.', assignor to George Morrell-Corp'oration, Muskegon, Mich.-, a corporation of Michigan No'Di-awing. Application July 8, 1940, Serial No. 344,459

I 4; 'Claims,.

v In the hardening of buttons, beads, disks and other articles made from plastic casein or'similar protein material, for example plastic casein to the extent of 50% "or more and soya bean protein comprising the remainder of a combined casein and soya bean plastic, it is common practice to subject the articles in a soft .unhardened state to a solution of formaldehyde which, commercially, is found in the market as a 40% solution of the formaldehyde gas in water or wood alcohol, under the trade names of Formalin and Formol. The articles are immersed in such bath, the normal commercial practice being to use a solution of a strength of 5 to per cent of formaldehyde in water. Such treatment results in the production of a non-putrifiable product of a hard character and of great durability. One example of the use of casein or like proteins treated in this manner is in the button industry, great quantities of buttons being commercially manufactured and marketed, the material .of

which consists wholly or largely of casein which has been thushardened and made durable by the formaldehyde treatment.

The curing and hardening of articles of this character in the formaldehyde solution requires a. great deal of time, the formaldehyde penetration occurring slowly. The length of time varies with thetemperature, concentration, j composition, and pH value of the formalin bath; and with these constant, it varies materially with the size, shape and mass of the protein-casein articles which are subjected to the curing or hardening treatment. As an example a disk or blank from which a button may be produced having a thickness between .140 and .160 inch will take from four to five days to harden in a 5% form-' aldehyde solution. The time varies to some extent with the diameter of such blanks a somewhat longer time being required with increases in diameter. Disks which have a thickness of approximately .230 inch immersed in a 5% formaldehyde solution require from nine to eleven days for hardening the longer time being required for disks of larger diameter and the shortertime for those of smaller diameter.

It is the primary object and purpose of the present invention to accelerate the formaldehyde The degree of penetration by the formaldehyde solution is largely controlled by the quantity of for uncured, that is, unhardened casein articles.

monium sulphate.

hardening of shaped protein plastic composition articles and materially reduce the time required for their complete and effective hardening.

Due to the hygroscopic nature of plastic casein,

,either with or without, soya bean constituents I therein, the uncured articles made therefrom contain widely varying percentages of water.

Moreover the uncured articles have been pre-. soaked in wateralone, the endeavor being to obtain penetration of the formaldehyde at an accelerated rate. v 7

Such attempts have not been satisfactory because of a serious disadvantage and characteristic of the product. The casein articles treated in such ways are solubilized, warp and swell to such an extent that often they adhere strongly together upon removal from such pre-soaking solutions.

-With' my invention these disadvantages are overcome and there is no adherence of articles to each other, nor excessive swelling or softening, eliminating the nuisance and damage which ocours to the articles in attempting to separate them when transferred to the formaldehyde hardening solution. According to my invention a pre-curing bath is used into which the disks, beads or other articles of casein protein or casein-soya bean protein or soya bean protein plastic composition are placed and submerged. Such bath consists of a solution of zinc salts in water. In practice a solution is used in which either zinc acetate, zinc chloride, zinc sulphate alone or two or more such salts mixed together, or hereinafter named zinc saltequivalents are dissolved in water, the percentage of the zinc salts used varying from 3' to 10 per cent of the 'quires materially less time than is required in the normal formalin hardening treatment.

The articles to be treated, before immersion in the formaldehyde solution are immersed in such solution and soaked for a period of from 12 to 24 hours; dependent up0n- The time required for hardening in the usual formaldehyde solution is reduced approximately 50%. In the previous example given where the thickness oi a disk was approximately .230 inch the normal process required from nine to eleven days for a proper hardening in a 5% solution of formaldehyde. The time in the formaldehyde solution to obtain satisfactory hardening was reduced to four days after a pre-soaking in a 5% zinc salts solution for 24 hours.

Such reduction of time required for the formaldehyde hardening is a matter of considerable practical value. For a given production, the

equipment and space required for the hardening,-

insoiar as the formaldehyde treatment is concerned, may be reduced approximately 50%. The cost of production is thus reduced both in a saving in floor space, cost of initial equipment and maintenance thereof. The advantage of using the pre-curing zinc salts solution at normal atmospheric temperatures, obviating the expense of equipment for heating and the cost of fuel is obvious. The invention has been extensively tested and is sure in its operations. The prehardening treatment, is one easily performed and not subject to appreciable variations in result, and is easily controlled.

Although certain specific salts have been named this invention does not limit itself to these particular zinc salts as any of the zinc salts or zinc double salt may be used. Although only casein protein or soya bean protein or a mixture of both have been mentioned in this application, it is to be understood that the same results will be obtained with all proteins which are likewise hardened by formaldehyde.

Having fully described my invention what I desire to claim and secure by Letters Patent'is as I follows:

1. The herein described process for accelerating the hardening of shaped articles made from dry extruded protein material, selected from the group consisting of casein, soy bean protein and mixtures thereof, which consists in soaking said articles for a predetermined time in a solution consisting solely of a zinc salt dissolved in water and thereafter subjecting such articles to immersion in a formaldehyde solution until thoroughly hardened.

2. A process of treatment of shaped articles made from a dry granular rotein composition, 50% of which at least is plastic casein, which consists in soaking said articles for a predetermined time in a bath comprising solely zinc salts dissolved in water.

3. The process of treating shaped articles made from a dry granular protein composition, one-half of which at least isplastic casein and the remainder soya bean protein prior to hardening said articles in a formaldehyde solution which consists, in soaking the articles in a solu-- tion of zinc salts only in water for a predetermined time, the quantity of the zinc salts dissolved in water varying between 3 to l0% of the solution.

4. The treatment of shaped articles made from a dry granular protein material, the principal ingredient of which is plastic casein which consists, in soaking said articles in a solution made wholly of zinc salts dissolved in water for a time generally not exceeding twenty-four hours at room temperature.

'SILVIO PELLERANO. 

